Most diagnostic techniques to predict liver failure are interpretable only in terms of gross liver function, not in terms of the function of specific structures such as receptors. Anatomical information related to liver function obtained by using radioactive and magnetic colloids (MRI) has proven to be both costly and relatively ineffective. To overcome these diagnostic limitations, the investigators plan to synthesize and characterize galactose-containing proteins and nanocolloids labeled with stable isotopes. Stable isotopes will be quantitated by neutron activation analysis. Our non-radioactive, nontoxic agents, directed to the asialoglycoprotein receptor of hepatocytes by galactose, are expected to be rapidly and specifically removed from the blood based upon the number of functional receptors in the liver. Kinetic modeling of the depletion of these agents in blood can estimate the number of functioning receptors in the liver. Receptor-targeted diagnostic agents combined with stable isotope labeling and neutron activation represent a technologically novel and potentially general approach to the design of agents to measure receptor function in the liver and other organs. Most importantly, stable isotope labeling offers an opportunity to measure multiple receptor activities simultaneously. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE